Deforestation

I had previously wondered here about the source for Al Gore's An Inconvenient Truth claim that 30 percent of CO2 was from forest burning. I'm reading this claim here by Nicholas Stern on Voxeu although the number is lower (probably because the base is greenhouse gases and not C02).
... there should be a coherent, integrated international programme to combat deforestation, which contributes 15-20% of greenhouse gas emissions...
Unfortunately, there is no source for this either although he notes this as a way to decrease GHG. Gore did not target this in his book which I had thought was a a large source of GHG.